1. Field of the Invention
The invention refers to an angularly adjustable, releasably lockable joint mechanism for rigidly joining first and second parts at a selected orientation, said mechanism comprise a rounded member having a plurality of concavities on its surface and being secured to the first part, a disengageable actuator having at least one tip and being operative to advance the tip to lock up with the rounded member by penetrating at least one concavity or to retract the tip to disengage it from the rounded member, said actuator being connected with the second part, and means for holding the parts, rounded member and actuator together, said means being motive to allow the parts to change relative orientation when the actuator tip is retracted.
This mechanism is particularly adapted for use with angularly adjustable, locking devices subject to high torsional forces.
2. Background Description
The present invention generally relates to an angularly adjustable releasably lockable joint mechanism for rigidly joining first and second parts at a selected orientation, and more particularly to an angularly adjustable releasably lockable joint mechanism having a plurality of patterned protuberances forming concavities so that a tip of actuator can engage and disengage therefrom.
Such a joint mechanism is disclosed for example in U.S. Pat. No. 5,280,871. A movable rod has a ball fixed at its bottom, and the ball is provided with a plurality of holes orderly and equally spaced apart in the surface for the functional end of a locating pin of a supporter to selectably engage one of them to keep the movable rod secured in an angle needed. Such a dimpled ball and an actuator having a spherical tip are also shown in U.S. Pat. No. 3,433,510. U.S. Pat. Nos. 3,841,769 and 4,620,813 show a socket having protuberances and a ball having dimples or indentations which engage to fix the orientation of the arms attached thereto. U.S. Pat. No. 3,691,788 shows a ball having a grooved surface and an actuator having a spherical tip which locks up by engaging a groove. U.S. Pat. No. 892,105 shows a ball and socket whose surfaces are both knurled.
Angularly adjustable, releasably lockable ball joints are commonly used as part of an umbrella assembly, to hold a suspended canopy locked at an angle to horizontal. Assemblies of this type are shown in U.S. Pat. No. 4,674,523 and U.S. Pat. No. 5,002,081. In general, these prior art ball joints involve:
a ball attached to a shank forming part of the suspension stand; PA1 an actuator or screw spindle carrying the canopy; PA1 a housing engaging the ball and spindle so that they cannot separate, but which is operative to enable the spindle to be angularly adjusted when the actuator is disengaged; and PA1 a concave socket or pin at the end of the spindle, for frictionally engaging the ball to lock the spindle and ball together and fix the canopy at a desired angle. PA1 the rounded member having a plurality of patterns of spaced-apart protuberances cornering at least part of its surface, the protuberances of each pattern forming a concavity therebetween; PA1 the patterns, and protuberances being mainly consistent in shape, area and size, the effective patterns having a regular polygonal conjuration; PA1 the protuberances, actuator tip and pattern being dimensioned so that the tip can penetrate the concavity of each pattern and simultaneously contacts all of the protuberances of the pattern that it penetrates but remains spaced from the bottom of the concavity at full penetration, whereby the tip and pattern of protuberances lock together. PA1 the locking capability is greater than one obtains with a dimpled ball; PA1 by arranging the patterns in accordance with a geometric designs the longitude and latitude of the concavity sites is predictable; PA1 the use of the triangular pattern yields a large number of concavity sites in the case of a rounded member that is spherical and of given diameter. Compared to an equivalent pattern of dimples, twice as many concavity sites result simply through the formation of the protuberances in place of the dimples; and PA1 it is possible to address and achieve locking at each individual position by electronic means, since all of the concavity sites or locking positions are mathematically definable.
The frictional engagement of ball and socket as well as a dimpled ball and spherical pin actuator have been found to be insufficient when subjected to high torsional forces.